McMillan returns to the Biggest Team in Glasgow from Wasps with whom he won the Heineken Cup and Guinness Premiership whilst Barker pulls on the black and blue jersey having played in Ireland and France with Ulster and Castres respectively.
Since their last game for the Warriors in the then Celtic League, both are anticipating a fierce contest as the competition has continued to go from strength to strength during their brief absence.
Barker said: "I really enjoyed my previous spell with Glasgow but there's now a greater degree of ambition and anticipation around the squad. The Magners League is now the most closely fought professional league in the world so it's an exciting competition to be involved in."
McMillan added: "I've been very impressed with the changes in both the Glasgow set-up and the level of competition in the Magners League.
"It's going to be fantastic to be part of the team again but it'll also be a tough first game. We've got the Dragons in Europe as well this year so whoever wins on Friday night will have the upper hand not only in our own League battle but our European one also."
Glasgow Warriors team to play Newport Gwent Dragons in the Magners League at Rodney Parade on Friday 5 September (kick-off 7:05pm)
15 Bernardo Stortoni
14 Lome Fa'atau
13 Max Evans
12 Graeme Morrison
11 Thom Evans
10 Dan Parks
9 Mark McMillan
1 Justin Va'a
2 Dougie Hall
3 Moray Low
4 Tim Barker
5 Alastair Kellock CAPTAIN
6 Kelly Brown
7 John Barclay
8 Johnnie Beattie
Substitutes
16 Eric Milligan
17 Kevin Tkachuk
18 Opeta Palepoi
19 Stevie Swindall
20 Colin Gregor
21 Andrew Henderson
22 Ruaridh Jackson
Guinness PRO12
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